SEASONAL-VARIATION IN VITAMIN-D, VITAMIN-D-BINDING PROTEIN, AND DEHYDROEPIANDROSTERONE - RISK OF PROSTATE-CANCER IN BLACK-AND-WHITE MEN

Our previous study provided evidence that higher serum levels of the a ctive form of vitamin D, 1,25-dihydroxyvitamin D (1, 25-D), might poss ibly slow the progression of subclinical to clinically significant pro state cancer in both black and white men, especially after age 57. Thi s paper extends the prior study by contrasting seasonal variation in 1 ,25-D and its precursor, 25-hydroxyvitamin D (25-D), in case and contr ol subjects, In addition, the risk of prostate cancer is related to se rum levels of vitamin D-binding protein (VDBP) and total dehydroepiand rosterone and to polymorphic variation in VDBP, The expected elevated summer levels of 25-D were seen in case and control subjects and, as e xpected, 1,25-D did not vary throughout the year in the control subjec ts. Unexpectedly, lower cas levels of 1,25-D were limited largely to t he summer months (P = 0.01) in both black and white cases and to cases greater than or equal to the median age of 57 years. Levels of VDBP a nd dehydroepiandrosterone and the frequencies of VDBP polymorphisms we re similar in case and control subjects, although striking differences were seen in allelic frequencies in black and white men, These observ ations provide additional evidence that vitamin D metabolism may impac t the risk of prostate cancer.